Development of the oil sands has led to increasing atmospheric N
deposition, with values as high as 17 kg N ha-1 yr-1; regional
background levels <2 kg N ha-1 yr-1. To examine responses to N
deposition, over five years, we experimentally applied N (as NH4NO3)
to a poor fen near Mariana Lake, Alberta, at rates of 0, 5, 10, 15,
20, and 25 kg N ha-1 yr-1, plus controls (no water or N addition).
Resin tubes filled with mixed-bed ion exchange resin were swapped in
and out at each collection/deployment date (mid-May and mid-October of
each year). Upon collection, resins were extracted with 1M KI and
analyzed for inorganic N concentrations. Over all ion exchange resin
tube collection dates, deposition of NH4+-N, NO3--N, and dissolved
inorganic N (DIN; NH4+-N + NO3--N) averaged 240 ± 29, 318 ± 27, and
557 ± 41 µg m-2 da-1, values that are equivalent to 0.87 ± 0.10, 1.16
± 0.10, and 2.03 ± 0.15 kg N ha-1 yr-1. While NH4+-N deposition was
higher in the growing season than in non-growing season (p = 0.0006),
NO3--N deposition was higher in non-growing season than during the
growing season (p = 0.0052), with the net result being no seasonal
difference in DIN deposition (p = 0.6428).